This present invention relates to a filter for use in fluid systems, and more particularly, the invention relates to a center support element for a filter.
Filters are typically constructed from a housing formed of one or more components secured to one another. A filter media, which is typically a pleated type filter media, is disposed within the interior cavity of the housing. The filter media is generally cylindrical in shape with an exterior surface defining an input side through which dirty fluid enters. The interior of the filter media defines a central fluid passage acting as an outlet side that receives the cleaned fluid.
Conventional filters include a center tube acting as a filter media support element, which confers to the assembly a certain amount of structural strength. The more common tubes which are used to form the central support are generally made of metal, and can be formed as spirals, as a corrugated shell which is closed with a lock seam, or as a robust cylinder which is welded. These various configurations can rust during storage or prolonged periods of non-use, and can be difficult to manufacture. The metallic centers cause a long term pollution problem, because they remain in the environment for a protracted time. Burrs can form during the machining, rolling and cutting processes to manufacture the filters, which can further increase the environmental hazard posed by the filters when they are discarded after use.
The present invention provides a center support for a liquid filtration element which is biodegradable, to reduce the environmental impact of the discarded filters. The center support may be made of plastic or other non ferrous materials, and for example may be incineratable to avoid the problem of storing the discarded filters in a landfill, or in other environmentally damaging manners.
According to the invention, the center support provides a high collapse strength without significantly increasing the assembled weight of the filter. In one exemplary embodiment, the center support has a truss design which provides a stronger and more robust support than is possible with other configurations. The inventive structure is disposed centrally, for example within the central opening of the filter media, and is shaped to permit the flow of fluid through the center fluid passage. The center tube assembly provides the desired structural integrity while permitting the cleaned fluid to flow through the center passage, to the filter outlet.
Fluid filters such as the oil filters in common use in the lubrication systems of engines are subject to a multitude of forces. During operation, the high pressure fluid enters the filter and passes through the filtration media, causing expansion forces to be applied to the can or housing of the filter as well as the filter media. Even greater forces are applied during mounting and removal of disposable filters. These filters use threaded or other fasteners to secure to a mounting plate of an engine, and considerable force may be applied to the filter using a variety of tools to fasten or to remove the filter from the mounting plate. These forces generally tend to crush the filter can or housing, so that the center support according to the invention is useful in preventing the collapse of the can or housing.
According to exemplary embodiments of the invention, the center support is formed of a non ferrous material which does not rust, and is easily disposed of after the filter is discarded. For example, a plastic material may be used. Disposal can be by incineration, or the bio-degradable material may be left in a landfill or other waste disposal location. To obtain the desired strength while minimizing the weight of the center support, and thus of the entire filter, a truss structure may be used.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.